import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.RandomAccessFile;


public class Main {
    private static final Long count = 1000000000l;
    public static void main(String[] args) throws InterruptedException{
        serial();
        concurrency();
    }
    private static void concurrency() throws InterruptedException{
        long start = System.currentTimeMillis();
        Thread thread = new Thread(new Runnable() {
            @Override
            public void run() {
                int a = 0;
                for (long i = 0;i < count;i ++){
                    a += 5;
                }
            }
        });
        thread.start();
        int b = 0 ;
        for (long i = 0;i < count;i ++){
            b--;
        }
        long time = System.currentTimeMillis() - start;
        thread.join();
        System.out.println("concurrency : "+time+"ms b="+b);
    }
    private  static void serial() throws InterruptedException{
        long start = System.currentTimeMillis();
        int a = 0;
        for (long i = 0;i < count;i++)
        {
            a += 5;
        }
        int b = 0;
        for (long i = 0;i < count;i ++)
        {
            b --;
        }
        long time = System.currentTimeMillis() - start;
        System.out.println("serial : "+time+"ms b = "+b);
    }
}
